In broadcasting methods known in the art such as terrestrial digital television broadcast, typically, as illustrated in FIG. 1, a channel (physical channel) is defined at every constant frequency interval to send an independent signal through each channel. In the example of FIG. 1, the frequency interval is set to 8 MHz, and a guard band having a predetermined bandwidth is set between each channel in terms of interchannel interference and the like.
In a case where a guard band is set between each channel, a bandwidth of a single channel is limited to a channel interval or less. A bandwidth of the signal output by the transmitter that generates a transmit signal corresponding to a single channel for transmitting program data and the like is set to a channel interval or less. For example, in the case of ISDB-T as a Japanese terrestrial digital broadcast standard, the channel interval is set to 6 MHz. Therefore, a bandwidth necessary in the transmitter (frequency bandwidth of the outputtable signal necessary in the transmitter) becomes approximately 6 MHz at maximum.